A photoluminescent material that emits visible light (generally, light with a wavelength of not less than 380 nm and less than 830 nm) by irradiation of light is used for lighting equipments, back light for liquid crystal display devices and the like. Regarding such photoluminescent material, various techniques have been proposed heretofore.
Patent document 1 describes an emission element containing an assembly of oligo atomic metal clusters confined in molecular sieves. Patent document 1 recites zeolite, porous oxide, silicoaluminophosphate, gallophosphate, zinc phosphate, titanosilicate, and aluminosilicate as molecular sieves. In patent document 1, however, photoluminescence was actually confirmed only in zeolite 3A containing silver cluster (Example 3). In addition, patent document 2 describes a silver-supporting zeolite fluorescent material obtained by a dry treatment under normal pressure at 100° C. or below.
Non-patent document 1 proposes use of a sodalite containing silver and oxalic acid anion as an optical data storage material.